| 100% | ESA | 3 | Intl. org. that was the first to land a probe on a comet (2014) |
| 44% | TASS | 4 | News agency that was the first to report on Sputnik |
| 44% | DICKBUTTON | 10 | *Olympic champion who, in 1948, was the first to land a double axel in competition |
| 44% | MYSPACE | 7 | Social networking giant of the '00s that was the first to reach a global audience |
| 43% | PALM | 4 | Co. that was the first to successfully market a PDA worldwide in 1997 |
| 43% | METS | 4 | M.L.B. team that was the first to trade a player for himself (Harry Chiti in 1962) |
| 43% | INC | 3 | Business magazine that, in 1981, was the first to feature Steve Jobs on its cover |
| 42% | REDDAWN | 7 | 1984 Patrick Swayze film that was the first to be released with a PG-13 rating |
| 42% | MARLINS | 7 | Florida squad that was the first to win two World Series titles as a wild-card team |
| 42% | NASA | 4 | Agency that plans to land a woman on the moon by 2024: Abbr. |
| 41% | ADRIATIC | 8 | RMS ___, British ship that was the first ocean liner to feature a swimming pool |
| 41% | LUKEAIKINS | 10 | American skydiver who was the first to land safely without a parachute or wingsuit from mid-tropospheric altitude: 2 wds. |
| 40% | ALABAMA | 7 | Montgomery's state that was the first US state to recognize Christmas as a holiday in 1836 |
| 40% | IKEA | 4 | Furniture store that was the first company to show a gay couple in an American TV commercial |
| 40% | BEA | 3 | Flyer that performed the world's first automatic landing on a commercial flight on June 10, 1965 (abbr.) |
| 40% | ITO | 3 | Olympic skater who was the first woman to land a triple axel in competition |
| 40% | ITO | 3 | Skater Midori who was the first woman to land a triple axel in competition |
| 40% | OMAR | 4 | Ilhan who was the first person to wear a hijab on the House floor |
| 39% | IKEA | 4 | Company that was the first in the U.S. to air a TV ad with a gay couple (1994) |
| 39% | KISS | 4 | "___ Me," song by Sixpence None the Richer that was the first song Taylor Swift learned to play on guitar |
| 39% | SUTTERSMALL | 11 | Historic shopping center that was the first to be called "a gold mine for investors"? |
| 39% | DESPACITO | 9 | 2017 hit that was the first Spanish-language song to reach No. 1 on the Billboard Hot 100 since "Macarena" |
| 39% | STELLAMARIS | 11 | 2022 prequel to "The Passenger" that is the first novel by 34-Across to feature a female protagonist (2 wds.) |
| 39% | BOOMBAYAH | 9 | 2020 51-Across song that was the first K-pop debut music video to pass one billion views on YouTube |
| 39% | USA | 3 | This nation's athlete is the first figure skater to land eight quads in a competition |
| 39% | SKYFALL | 7 | 2012 Adele hit that was the first James Bond theme to debut in the top 10 on Billboard's Hot 100 |
| 39% | RETTON | 6 | Gymnast Mary Lou who was the first woman to appear on the front of a Wheaties box |
| 38% | MARIA | 5 | ___ Mitchell, astronomer who was the first female professor of astronomy and the first American to discover a comet |
| 38% | ODYSSEUS | 8 | Robot that landed on the moon in February 2024, marking the first moon landing by a private company |
| 38% | ECLAIR | 6 | Pastry that becomes a name when the first letter is moved to the end |